Lapping machine



g- 1933. c. E. PARKHURST 1,923,390

LAPPING MACHINE Filed Feb. 15, 1932 2 Sheets-Sheet 1 M ATTORNEY."

Aug. 22, 1933. c. E. PARKHURST ,923,390

LAPPING MACHINE Filed Feb. 15, 1932 2 Sheets-Sheet 2 Fig [7 I Z0,PINVENTOR. I BY WflLI/PY, 7%RMMZ M ATTORNEY.

Patented Aug. 22, 1933 LAPPING MACHINE Clyde E. Parkhurst, Moline, Ill.,assignor to Moline Tool Company, Moline, 111.

Application February 15, 1932.7 Serial No. 593,015

1 Claims. (01. 51-1843) f My invention has reference to a lapping orhoning machine, and as set forth herein it embodies a mechanism morespecially designed for use on the inner wall of a brake drum, or

5 other cylindrical body having a closure or other obstacle at one ofits ends or within its bore, which interferes with the movement of thelapping tool entirely through the piece of worle.

'The invention consists of alapping head, supported by a spindle in theusual manner, so as to be capable of a rotary movement, and also movableaxially, for translation of the head toward and into a piece of work andthe consequent retraction of the head therefrom. lhe head is of circularformation, and is provided at intervals on its periphery with stones of,abrasivematerial. By means of other instrumentalities carried by thelapping head the stones may be adapted and adjusted to their work..

Stones of the kind mentioned are usually in the form of blocks of 'alength corresponding approximately with that of the head with which theyare connected, and in the performance of said blocks they are movedgradually into the part that is. being honed, with the result that theends of the stones which first enter the piece of work perform a greaterpart of the opstones thatfollow,

eration than the ends-oi the and possibly enter the work for a shortdistance only. As a result the stones become worn unevenly, with atendency to assumea wedge or tapered form, with the face of thestoneinclined from one end to the other, rendering the same inefficientand useless carding thereof.

One of the purposes of the present invention is to provide supports forthestonesof. such a character that they can be quickly reversed inposition upon becoming worn, as above mentioned, and, upon being againput in use, neutralize and correct the unequal condition.

Another feature of the invention consists in the provision of novelmechanism for the adjustr ment of the stones to their work, so as togradually increase the working circumference of the tool as the workprogresses. Associated therewith is means for holding the stonesyieldably against outward movement.v f

The above named, and other features and advantages of the invention willmore fully appear from the following specification, reference being hadto the accompanying drawings, in which;

Fig. 1 is a vertical medial section of a lapy The reference number bymeans of bolts 5.

and calling for the disping head, as it appears in operation in a drum,which is also sectioned.

Fig. 2 is a horizontal section line '2-2 of Fig. 1. i i

Fig. 3 is afragmentary view of the outer rim of the lapping head,showingone oithe stones 33 and the manner of reversing the positionthereof. 4 The figures of the drawings areconfined to the lapping headand parts'immediately asso-- ciated therewith, it being understood thatsaid mechanism-s form parts of a. larger machine; containing the usualfeeding and driving elements for the head.

brakeon the broken 1 indicates a spindle, 7 vertically disposed as setforth herein, to the. lower'end of which spindle is connected a.coupling 2, provided with an annular flange 3, with which is connectedthe web 4 of a lapping head,

Projected downwardly fromsaid web is a circulr head 6, centrally ofwhich is a cylindrical core l also depending from the web portion 4. In.the wall of the head 6 is a pluralityof bushings 8, in which areslid-ably and rotatably mounted shafts 9, so

reduced at their inner endsinto pins 10, rotata-, bly mounted inbearings 11 in the core 7. The ends of the pins 10 are beveled at 12to-con form to the lower part of a cylindrical expansion elementl3'supported in the core 7 so as to be movable freely therein. The lowerpart 14 of said element is in the form of an inverted frustum, and saidexpansion element is supported entirely by the ends of the inwardlyprojecting pins 10, so as to move freely or 901 float in said core. I

In the upper end of the element 13 is a recess 15, containing ananti-friction ball 16, upon which rests the lower end of a rod 17,passing upwardly through an opening 18 in the lower part of the coupling2 and a bore 19 in the lower end of the spindle 1. Fixed to the upper.end of the rod 17 is a cross-pin 20, the ends of which pass outwardlythrough a slot 21 in the spindle l, and are connectedwith a collar 22slidable on said spindle. On the lower end of the spindle 1 is mounted aplate 23, separated from the spindle by a ball-bearing outfit at 24,permitting rotation of the spindle independently of said plate. At oneend the plate 23 is 10 extended into an arm 25, shown partly brokenaway, and designed for a vertical slidable' connection with a fixture inproximity to the lapping head, as, for instance, the main column of themachine. llQ

I at 36, and having an end portion at 36*, par- 7 Supported on the plate23 is a bracket 26 in which is pivoted one end of a yoke-arm 27, andprovided at its other end with a recess 28- in which is pivoted anupwardly extended bolt 29. On the threaded end 30 of said bolt isa'thumbnut 31, by the proper operation of which the yoke-arm 2'7 and rod1'? can be forced downwardly, imparting a similar movement to theexpansion element 13. l

To the outer ends of the shafts 9 are attached shoes 33, held loosely inrecesses 34 in the rim of the head 6, transversely of said rim. Fixed insaid shoes are stones 35, of suitable abrasive material, and adapted foroperation in the inner wall of an automobile brakedrum, indicated tiallyclosing the same, and limiting the move.- ment of the stones downwardly.On each of the shafts 9 is a coiled spring '37, interposed between thebushing 8 and a collar-nut 38, having a threaded engagement with theshaft, for adjustment thereon to increase or diminish the force of thespring. As the stones 35 are fed into the workthe lower ends thereofsustain the greater amount of wear, and as the stones become worn so asto be out of true they may be inverted in position, by engaging the endsthereof with the fingers of the hand and drawing the stone and itsmounting outwardly until they'are clear of the head 6.- The stone andits shoe can then be turned end for end, in the mannershown in brokenlines in Fig. 3, and said parts re-seated in the 011%1'11181'34, In thisoperation the spring 3'7 is compressed, increasing the tension thereof,and upon the'stone being released it is again held yieldably in place bythe spring.

It will be noted that the action of the mech-' anism for radialadjustment of the stones is a positive one, and works against the forceof the springs 3'7. When the work of the tool is started in a brake-drumthe stones are properly positioned by the operation of the thumb-nut 31,and as the work proceeds the wear upon the stones or upon the wall ofthe drum can be compensated for by additional adjustment of thethumb-nut, to further expand the circle of the abrasive elements.

The stones 35 and their supporting shoes are formed to projectdownwardly beyond the wall of the'head 6, as shown, so as to give ampleclearance for said stones in the lower part of the drum.

What I claim, and desire to secure by Letters Patent, is:

1. In a lapping machine, a spindle mounted to rotate and reciprocate, acircular head fixed to said spindle, a plurality of stones mountedpivotally on the periphery of said head, and means for holding saidstones normally and yieldably against a reversal in position.

2. In a lapping machine, a spindle mounted for rotation andreciprocation, a head fixed to said spindle comprising an outer circularwall provided in its rim with transverse channels and a centralcylindrical mounting, spaced from said wall, a plurality 'of-shaftsjournalled in said wall atone end and in the mounting at the other end,and having extensions into said mounting, shoes fixed to the outer endsof said shafts and normally positioned in said channels, stones fixed insaid shoes, springs on said shafts holding the same with said shoes heldyieldably in said channels, and an expansion element in said mounting,bearing against the ends of said shafts, and operating against the forceof said springs.

3. In a lapping machine, a spindle mounted therein for rotation andmovement longitudinally, a head fixed to said spindle comprising anouter circular wall provided in its rim with spaces for stone holdingtools and a central cylindrical mounting, a plurality of supports heldrotatably and slidably in said wall and mounting and extending into themounting, stone holding tools fixed to the outer ends of said supports,and normally occupying said spaces, stones carried by said tools, saidtools being capable of being rotatably shifted in position upon beingwithdrawn from said spaces,

springs connected with said supports, and holding the same with saidstone holding tools held yieldably in said spaces, an expansion elementin said mounting, engaging the ends of said supports, and 'mea-ns'foradjustment of said expansion element to move said stones outwardlyagainst the force of said springs.

4. In a lapping machine, a spindle mounted therein for rotation andreciprocation, a head fixed to said spindle and provided in its rim withstone holding spaces and having a central cavity, supports extendingoutwardly from said central cavity to said spaces, stone holding toolsfixed to the outer ends of said supports, stones carried by said tools,springs onsaid supports holding the same yieldably in'inward positions,an expansion element in said cavity in engagement with the inner ends ofsaid supports, a plate supported on said spindle and provided with meansfor, slidable connection with a fixture,adjustment devices on saidplate, and means for imparting the movement ofsaid adjustment devices tosaid expansion elementto move said supports outwardly against thetension of said springs. I

CLYDE E. PARKHURST.

